The invention relates to a method for manufacturing diamond or diamond-like material from a form of carbon such as graphite.
The synthesis of diamond from graphite or C60 (fullerenes) requires the action of a high pressure on the graphite. Static methods are known for this on the one hand but also dynamic methods on the other hand.
In the static methods, graphite is compressed at a high temperature for a long period of time. Under standard conditions, the conversion of graphite to polycrystalline diamond begins at pressures above 12 GPa (1 GPa=10 kbar) and temperatures in the range of 2700° C. (Bundy, 1962, J. Chem. Phys.). In order for the conversion to take place more rapidly, one may even use a pressure of approximately 15 GPa and 3000° C. These ranges are complex and expensive to achieve industrially. However, with the help of metallic catalysts (usually a metal melt), the reaction conditions may be lowered to approx. 1500° C. and 6 GPa, which is thus a more realistic order of magnitude from the standpoint of efficiency.
The group of dynamic methods requires much lower temperatures in comparison with the static methods.
One known example of a dynamic method for diamond synthesis is the conversion of graphite by compacting the graphite with the help of explosive shockwaves (Decarli and Jamieson, 1961, Science). The resulting diamond created by high pressure cools off so rapidly that the characteristic diamond structure is obtained even at room temperature. The conversion of graphite to diamond also involves a martensite-like conversion, which requires only a few nanoseconds (Erskine and Nellis, 1991, Nature).
According to another dynamic method, the high pressure for the conversion is created by cavitation in an ultrasonic bath. The graphite here is in an organic solution at room temperature. The disadvantage of this method for commercial use is that typically a diamond yield of only 1% to 2% has been achieved in laboratory experiments so far.
The object of the present invention is to provide an efficient method for manufacturing diamond or diamond-like carbon, hereinafter also referred to as DLC (diamond-like carbon) from another form of carbon.